This chef’s trick for sharpening kitchen knives will have you prepping like a pro

A sharp knife is a chef’s best friend in the kitchen. No matter how skilled you are, a dull blade can make prep work tedious and time-consuming. But keeping your knives constantly sharp is easier said than done. Honing steels only straighten the edge temporarily, and trips to a professional sharpener can get expensive.

Luckily, this chef has a simple trick that will have your knives slicing through fruits and veggies like butter in no time. And the best part—you can do it yourself at home!

Why Knife Sharpening Matters

When knives become dull in the kitchen, you have to put in extra effort to chop, slice, and dice ingredients. A sharp blade glides right through foods with minimal pressure, avoiding slipping and inconsistent cuts.

Having razor-sharp knives allows you to work faster and with more precision. You’ll breeze through tasks like dicing onions, mincing garlic, slicing meats, and chopping herbs. Food preps that once took 15-20 minutes might only take 5-10 minutes with sharp knives.

Aside from speed and efficiency, sharp knives are also safer to use. You have more control over the blade and better accuracy for clean cuts. The knife does the work—not extra force from your hands.

How Knives Become Dull in the Kitchen

Knives naturally become dull with use over time as the extremely fine edge degrades. The more you use the knife, the quicker it loses its sharpness. These factors speed up the process:

  • Cutting hard materials like butternut squash and frozen foods
  • Using a cutting motion that grinds the edge against the board
  • Cutting acidic foods like tomatoes and citrus
  • Putting knives in the dishwasher
  • Storing knives improperly

Even high-quality knives made from hard steel eventually require sharpening. While honing steels realign the edge, they do not actually sharpen or remove metal.

The Chef’s Simple Trick for Sharpening Knives

Professional knife sharpening services can sharpen your knives for you. However, they are inconvenient and cost money each time. Purchasing your own sharpening tools like whetstones also has a learning curve.

Luckily, this chef has a fast and easy sharpening method using stuff you already have at home.

What You’ll Need

  • Kitchen or butcher’s knife that needs sharpening
  • Coffee mug
  • Piece of aluminum foil
  • Scissors
  • Sharpie marker

Step-by-Step Instructions

  1. Take a sheet of aluminum foil and fold it in half twice so you have a square about 5 inches wide.
  2. Use the scissors to cut the aluminum foil, making confetti-like scraps. Place the aluminum scraps into the bottom of a coffee mug.
  3. Use the Sharpie to mark the bottom 1/3 of the knife blade. This will help you keep track of what portion you sharpen.
  4. Holding the knife vertically, vigorously rub the marked portion of the blade up and down against the aluminum scraps in the mug, maintaining moderate pressure. Use a circular motion to keep the scratches randomized.
  5. Continue for 5-10 minutes. Check for burrs by running your finger from spine to edge. Remove any burrs by rubbing the blade on the aluminum away from the edge.
  6. Flip the knife over and repeat on the other side for 5-10 minutes with moderate pressure.
  7. Test the edge. Carefully slice through a tomato or piece of paper. Repeat steps 4-6 if needed.

The aluminum scraps remove a tiny amount of metal, literally shaving and grinding the edge into sharpness. In just 10-20 minutes, you can restore an incredibly sharp edge to your kitchen knives using this trick.

Getting An Even Sharper Edge

For an even keener edge, strop the knife after sharpening with the aluminum and mug. Here’s how:

  • Get a leather belt or sturdy denim. An old belt works great.
  • Hold the leather taut and run the knife over it,trailing edge only.
  • Go back and forth steadily with light pressure.
  • Repeat on the other side of the blade.
  • Rinse and dry the knife. Test the sharp edge.

The stropping further hones and polishes the edge, aligning the microscopic teeth even more. This makes the edge ridiculously sharp and smooth.

Maintaining Sharp Kitchen Knives

Sharpen your knives regularly so they don’t have a chance to get very dull. Any of these signs mean it’s time to sharpen:

  • Knife doesn’t glide smoothly through foods.
  • You’re putting extra force or weight on the knife.
  • Foods stick to the blade when slicing.
  • Chopped edges are ragged or inconsistent.

Avoid these mistakes that will ruin your sharp edge faster:

  • Scraping the blade edge on the cutting board.
  • Plunging it into hard objects.
  • Putting it loose in a utensil drawer.
  • Cutting through bones.

Store knives properly in a knife block, sheath, or on a magnet strip. Never put them loose in drawers.

Hon Steel your knives before and after each use to keep the edges straight. Avoid cutting acidic foods for long periods.

Getting Your Knives Professionally Sharpened

While this aluminum foil trick works great for quick, home sharpening, occasional professional sharpening has benefits too.

Pros use specialized equipment to sharpen to about 15-20 degrees per side, even sharper than home methods. They remove more metal and fix chips or dents.

Consider professional sharpening every 6-12 months for kitchen knives that see heavy use. Let the pros sharpen your most damaged or expensive knives.

In-between, use this mug trick to touch up the edges quickly.

FAQ About This Chef’s Knife Sharpening Trick

Here are answers to some frequently asked questions about this homemade knife sharpening technique.

Why use aluminum foil in a mug?

  • The aluminum scraps act as an abrasive when rubbed against the steel knife blade. This abrades away dull metal and grinds a new sharp edge.
  • Putting the aluminum in a mug holds it steady so you can sharpen safely and easily. Mugs are made from ceramic and won’t get damaged.

Does it matter what type of knife I sharpen this way?

  • This aluminum trick works for most kitchen knife types including chef’s knives, paring knives, boning knives, and utility knives.
  • For delicate Japanese knives, consider a whetstone instead. Check the knife manufacturer instructions.

What grit do the aluminum scraps equate to?

  • Aluminum is a soft metal, so the scraps act like a coarse sharpening material. The edges are random, not uniform like sandpaper.
  • In terms of whetstone grits, aluminum foil scraps are similar to a 200-400 grit stone.

How long does the sharp edge from this method last?

  • For light home kitchen use, expect the edge to last 1-2 weeks on average. High use or cutting hard foods may require re-sharpening after just a few days.
  • Avoid cutting frozen foods, bones, and other abrasive stuff to prolong the sharp edge. Use a honing steel frequently.

Can I cut myself doing this?

  • Yes, take care as this method involves vigorously rubbing a knife blade near your hand. Work slowly and cautiously.
  • Never sharpen towards yourself. Don’t wrap your fingers around the blade. Consider a cut-resistant glove for your holding hand.

Why stropping with leather after sharpening?

  • Stropping further aligns and polishes the microscopic teeth on the blade edge. This refines the edge to a crazy-sharp level.
  • The flexible leather helps remove tiny burrs or imperfections for an incredibly smooth, sharp edge.


Dull kitchen knives can make prep work a chore. While sharpening stones have a learning curve, this simple aluminum and coffee mug trick lets you sharpen knives quickly at home. For only the cost of foil and 10 minutes, you can restore razor sharp edges. Remember to strop after sharpening and hone blades regularly. Invest in an occasional professional sharpening so your knives stay surgical. With sharp knives, you’ll breeze through slicing, chopping, and dicing like the pros.